Donald 'Carolina' Biermann arrived at Angola prison in 1980. It was America's most violent jail, a Deep South sinkhole for killers and rapists. 'I came to Angola with the sole intent of dying here. I just did not care,' said the burly 48-year-old South Carolinian serving a life sentence for murder.

But things have changed in this sprawling Louisiana jail that inspired Hollywood films such as Monster's Ball and Dead Man Walking. Biermann, once a feared inmate, is now in his second year at a seminary that has opened inside the prison.

He hosts a Bible class for fellow prisoners on his wing each Thursday. 'Jesus took the hate out of my heart,' he said with the glazed conviction of a true believer. Around his thick necks hangs a shiny crucifix made of prison-issue screws.

Biermann is not alone. Angola, America's largest maximum security prison, has undergone a transformation: it has found God. Controversial warden Burl Cain has opened the prison doors to religious groups like no other jail in America. The result has been a stunning decrease in violence. In 1995, Angola saw 799 incidents of inmates attacking each other and 192 attacks on guards. This year the figures so far are just 78 inmate-on-inmate assaults and 19 on staff.

Angola is dominated by religion. Pastors and preachers flock for visits. Its seminary is the only one of its kind in the US. Hundreds of prisoners are taking its four-year course; scores have graduated as ministers. Religious radio pumps through the prison 24 hours a day.

Next month, a similar seminary, modelled on Angola, will open in a jail in neighbouring Mississippi. Florida and Alabama are also studying the idea. What has happened in Angola could spread all over the South.

But for some Cain has gone too far. He has been criticised by the American Civil Liberties Union for blurring the cherished line between church and state. 'Endorsing religion like this is going over the line,' a spokesman said. For some, the prospect of Christian fundamentalists in control of a prison is a source of worry and fear. A Louisiana state senator, Don Cravins, recently complained that Cain's rule at Angola was too authoritarian. 'There is no accountability,' he said.

Angola does seem a world unto itself. Its 18,000 acres (larger than Manhattan) are surrounded on three sides by the Mississippi river. Its fourth side hides behind densely wooded hills. It was once a slave breeding plantation, named after the part of Africa where its miserable captives were born. In 1901 it was taken over as a state prison and is now home to 5,108 inmates.

It is still a place of unique horror. In Louisiana a life sentence means you will die in prison. In Angola more than four out of five inmates have life sentences. They know that they will leave the jail's embrace only in their coffins. Unsurprisingly, Angola has always been famed for brutality, riots, escape and murder. That was something Biermann knew all about. For years, the jail's violence was his way of life.

'I have done things that people would say are inhuman,' he said bluntly. 'A lot of the people I have done them to are still in here.'

All that changed with Cain. As violence levels have fallen, so chapels have sprouted in Angola's prison camps. A freshly painted white spire stands over Camp C. Another chapel is half-built at Camp F. A gift of $200,000 will kick-start work on a new, much enlarged, chapel for the main camp. All are built with inmate labour. Sitting at the same wooden table at which he attends a weekly Bible class with his wardens, Cain is unashamed of his religious beliefs. He cuts a very Southern figure, with a rich accent and speech littered with homely sayings. But he is blunt about what is happening at Angola: 'God is working through this prison.'

Cain knows his jail intimately. As he speaks he constantly takes phone calls: one to arrange a free eye operation for an inmate, another to discuss the firing of a warden recently arrested for having sex with a 13-year-old. He holds the hands of Death Row prisoners as they die in Angola's execution room. Cain's face is the last thing they see. And it was in that spartan chamber that Cain first realised he had to change Angola.

'When I came here I had been a warden for 13 years. I had just done it like I always had done it. Then I saw the first execution,' he said. 'We didn't say anything to the guy about his soul. I just thought "What we are going to do to make this place better?"' Cain decided that religion was the answer.

In his nine years in charge of Angola, Cain has also decided that many inmates need a second chance. Life should not always mean life.

'We are wasting human beings. Prison should be a place for predators, not for dying old men. Some old men are predators and they can stay but we need to tell the difference,' he said. Cain says he knows many inmates who he believes should be let out, but is adamant he is no liberal: 'We are not soft.'

No one who spends any time inside Angola can think it is a soft regime. It still looks like a slave plantation. Like 19th-century photographs come to life, work teams of mostly black prisoners march daily into the fields to toil under the Louisiana sun. It is backbreaking labour among cotton and corn. Watching them are mounted guards cradling rifles. Prisoners are paid just four cents an hour. In the punishment block, J-Block, inmates can spend 23 hours a day in their cells. Several have spent more than 30 years in solitary confinement.

Given the hopelessness of most prisoners, perhaps it is not surprising that the seminary has been such a success. The college sits incongruously in the main prison camp marked by the sign 'Baptist Theological Seminary'. Inside, Chaplain Robert Toney sat in a room lined with Bibles and one book entitled Making Peace With Your Past. Inmates go to class from 8am to 3pm daily. 'They get the same qualification as students on the outside, take the same exams and study the same books,' he said.

It is a tough course for some prisoners, many practically illiterate. But it gives their lives purpose. William Fallon, 26, a handsome man with a neat haircut, is serving life for murder. Now a born-again Christian, he is in no doubt where he would be without the seminary. 'I would probably be dead. If not dead, then insane,' he said. Fallon showed off his T-shirt. On his chest was a verse from the Bible: 'Then the Lord answered Job from the whirlwind.' He spun around to proudly show off the T-shirt's back. 'See me coming through Angola like a whirlwind,' it read.

Angola's seminary is now producing convict missionaries. Ron Hicks, 34, also serving life for murder, hopes to be one of them. He is a graduate of the seminary and would like to preach in other jails. 'It all depends on where God calls me,' he said. 'You can walk through my wing now and see the games room with people praying. You see Bible studies going on.' So far 13 graduates, trained to spread their religion, have left Angola to serve their sentences in other jails. They have set up their own ministries in their new prisons. Perhaps, finally, there is a way past Angola's razor wire and walls.